U.S. patent number 6,106,855 [Application Number 08/035,002] was granted by the patent office on 2000-08-22 for protein stabilized oil-in-water emulsions.
This patent grant is currently assigned to Johnson & Johnson Medical, Inc.. Invention is credited to Wilson Harvey, Carla A. Haynes.
United States Patent |
6,106,855 |
Haynes , et al. |
August 22, 2000 |
Protein stabilized oil-in-water emulsions
Abstract
Stable oil-in-water emulsions are prepared by mixing oil, water
and an insoluble protein at high shear. By varying the amount of
insoluble protein the emulsions may be made liquid, semisolid or
solid. The preferred insoluble proteins are insoluble fibrous
proteins such as collagen. The emulsions may be medicated with
hydrophilic or hydrophobic pharmacologically active agents and are
useful as or in wound dressings or ointments.
Inventors: |
Haynes; Carla A. (Cambuslang,
GB), Harvey; Wilson (Gargunnock, GB) |
Assignee: |
Johnson & Johnson Medical,
Inc. (Arlington, TX)
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Family
ID: |
10712827 |
Appl.
No.: |
08/035,002 |
Filed: |
March 22, 1993 |
Foreign Application Priority Data
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Mar 25, 1992 [GB] |
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9206508 |
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Current U.S.
Class: |
424/445; 424/444;
424/449 |
Current CPC
Class: |
A61Q
19/00 (20130101); A61K 8/06 (20130101); A61K
8/062 (20130101); A61K 8/64 (20130101); A61K
8/65 (20130101); A61K 8/922 (20130101); A61L
27/22 (20130101); A61K 9/1617 (20130101); A61K
9/1658 (20130101); A61K 9/7007 (20130101); A61K
47/42 (20130101); A61L 26/0028 (20130101); A61K
9/0063 (20130101) |
Current International
Class: |
A61K
8/30 (20060101); A61K 8/64 (20060101); A61K
8/65 (20060101); A61K 8/92 (20060101); A61K
9/00 (20060101); A61K 9/16 (20060101); A61K
9/70 (20060101); A61K 47/42 (20060101); A61L
27/22 (20060101); A61L 27/00 (20060101); A61K
6/00 (20060101); A61L 26/00 (20060101); A61K
8/06 (20060101); A61K 8/04 (20060101); A61Q
19/00 (20060101); A61L 015/00 () |
Field of
Search: |
;424/445,DIG.13,443
;514/938,939,944,887,801 |
References Cited
[Referenced By]
U.S. Patent Documents
Foreign Patent Documents
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0 532 119 A1 |
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Mar 1993 |
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EP |
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6652 M |
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Dec 1966 |
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FR |
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55-84167 |
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Jun 1980 |
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JP |
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034923 |
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Dec 1985 |
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JP |
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2 058 084 |
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Sep 1980 |
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GB |
|
Other References
Collagen Sponge: Theory and Practice of Medical Applications; J.
Biomed. Mater. Res., vol. 11, pp. 721-741 (1977), Milos Chvapil.
.
Collagen Biomaterials Characteristics and Applications; JALCA, vol.
80, pp. 195-212 (1985), Alain Huc. .
Derwent WPI Abstract JP-A-55082621, Jun. 21., 1980. .
Derwent WPI Abstract JP-B-85034923, Jun. 25, 1980. .
Eaglstein et al. (1980). J. Inv. Dermatol. 74(2) : 90-91..
|
Primary Examiner: Page; Thurman K.
Assistant Examiner: Benston, Jr.; William E.
Attorney, Agent or Firm: Riesenfeld; James Farmer; Andrew C.
Shatynski; Theodore J.
Claims
We claim:
1. A method of treating burns or wounds comprising applying to the
surface of the burn or wound an effective amount to treat the burn
or wound of an oil-in-water emulsion comprising, prior to its
application, from 1% to 50% by weight of an oil, from 0.5% to 25%
by weight of an insoluble protein and from 25% to 98.5% by weight
of water.
2. A method according to claim 1 wherein the oil in the oil in
water emulsion is present in an amount of from 10% to 35% by
weight.
3. A method according to claim 1 wherein the insoluble protein of
the oil in water emulsion is present in an amount of from 1% to 15%
by weight.
4. A method according to claim 1 wherein the insoluble protein
comprises an insoluble fibrous protein.
5. A method according to claim 4 wherein the insoluble fibrous
protein is selected from the group consisting of collagen, keratin,
fibrin, elastin, and mixtures thereof.
6. A method according to claim 1 wherein the oil and water emulsion
further comprises up to 20% by weight of a soluble biopolymer or
biopolymer derivative.
7. A method according to claim 6 wherein the soluble biopolymer or
biopolymer derivative is selected from the group consisting of
gelatin, pepsin solubilized collagen, alginates, hyaluronic acid
and derivatives and mixtures thereof.
8. A method according to claim 1 wherein the oil and water emulsion
further comprises a pharmacologically active agent.
9. A method according to claim 8 wherein the pharmacologically
active agent is selected from the group consisting of antiseptics,
antibiotics, growth factors, hormones, cytokines and peptides.
Description
This invention relates to oil-in-water emulsions stabilized by the
presence of insoluble protein in the aqueous phase. The
compositions are suitable for use as or in wound dressings.
Biopolymers, such as animal proteins and plant polysaccharides,
have been used in recent years in a number of diverse applications,
including biomedical applications. For example, alginates (which
are polysaccharides derived from seaweeds) are valuable for their
haemostatic properties, while collagen (the major protein of skin
and connective tissue) has been used in wound dressing materials,
as well as in surgical sponges (see, for example, U.S. Pat. Nos.
3,632,361; 4,412,947; 3,823,212; Chvapil, J. Biomed. Mater. Res.
11, 721 to 741 (1977); Huc, J. Am. Leather Chem. Assoc. 80, 195 to
212 (1985)1; and GB-A-2058084). Collagen is attractive in a
biomedical context, principally because it is biocompatible,
resorbable, structurally versatile and also has haemostatic
properties.
Japanese laid-open patent application JP-A-55084167 (Lion Hamigaki
KK) describes medicated sponge bands for the treatment of
periodontal disease. The sponge bands comprise a sponge matrix of a
soluble polymer having droplets of non-volatile oil dispersed
therein. The non-volatile oil may contain dissolved medicaments.
The sponge bands are formed by freeze drying an oil-in-water
emulsion having the soluble polymer dissolved in the aqueous phase.
The soluble polymers may be natural, synthetic or semi-synthetic
polymers such as cellulose derivatives, natural gums, sodium
alginate, gelatin or polyvinylpyrrolidone. In use, the medicated
sponge bands are applied to affected areas such as mucous membranes
in the oral cavity. The bands rapidly absorb water to form a sticky
oil-in-water ointment. The sponge band is normally provided with an
impermeable backing layer to improve the persistence of the
ointment at the affected area.
The present invention is based on the discovery that insoluble
proteins such as fibrous collagen are effective emulsifiers. The
resulting oil-in-water emulsions having insoluble protein in the
aqueous phase are suitable for use as wound contacting materials in
wound dressings.
According to the present invention there is provided an
oil-in-water emulsion comprising from 1% to 50% by weight of an
oil, from 0.5% to 25% by weight of an insoluble protein and from
25% to 98.5% by weight of water.
Preferably, the oil-in-water emulsion comprises from 10% to 35% by
weight of the oil. The term "oil" includes all oleaginous materials
that are liquid or semisolid at temperatures below 40.degree. C.
Preferred oils include mineral oils and vegetable oils such as
sesame seed oil, rapeseed oil, sunflower oil, arachis oil, or corn
oil.
The consistency of the oil-in-water emulsions ranges from liquid to
semi-solid to solid at 25.degree. C., depending on the insoluble
protein content. Preferred emulsions contain between 1% and 15% of
the insoluble protein. Lower protein content generally results in
an emulsion having a semi solid gel or paste-like consistency at
25.degree. C. and therefore useful as a wound dressing ointment.
Emulsions containing more than about 5% by weight of the insoluble
protein generally have a more solid or waxy consistency and are
suitable for use as the wound contacting layer of multilayered
wound dressings. Cast or extruded into films these emulsions can
themselves be applied directly as wound dressings.
Oil-in-water emulsions according to the present invention may also
be characterised by their penetrability. The penetrability is
defined by reference to the force in Newtons required to compress
or penetrate the emulsion by 10 mm using a cylindrical steel probe
15 mm in diameter at a speed of 130 mm/minute. The force is
preferably from 0.1 to 20 Newtons, more preferably from 0.5 to 15
Newtons, and most preferably from 1 to 10 Newtons.
The insoluble protein may be a naturally occurring insoluble
protein such as an insoluble fibrous protein. Alternatively, the
insoluble protein may be a soluble protein such as gelatin that has
been cross-linked to render it insoluble. Suitable cross-linking
agents include HMDI (hexamethylene diisocyanate), water soluble
carbodiimide or glutaraldehyde. In other embodiments the insoluble
protein may in fact be a soluble protein that is present in the
aqueous phase at concentrations above its solubility limit. In yet
other embodiments the insoluble protein may be precipitated from
solution in situ--for example, collagen fibres can be precipitated
from collagen solutions by either adding polyethylene glycol at
neutral pH as described in U.S. Pat. No. 4,980,403, or by adding
salts, or by forming a gel of soluble collagen at 37.degree. C.,
mechanically disrupting the gel, centrifuging and retaining the
resulting fibrous pellet as described in U.S. Pat. No. 4,655,980.
All of the above embodiments are included within the scope of the
present invention.
Suitable insoluble fibrous proteins preferred for the process of
the invention may include the so-called structural fibrous proteins
and derivatives thereof, such as insoluble collagen, keratin,
fibrin and elastin.
Preferably, the insoluble fibrous protein is predominantly
comprised of insoluble collagen, which may suitably be obtained
from bovine skin. Such collagen preferably has a fibre length of
from 0.005 to 5 mm, and more preferably from 0.01 to 3 mm.
Conveniently, but not essentially, the collagen is swollen prior to
use, either in acid or in alkali. Acid
swelling is preferred, with optimum swelling occurring in the pH
range 2 to 3.5. Organic acids (e.g. acetic acid, malic acid, lactic
acid and citric acid) and mineral acids (e.g. hydrochloric acid and
sulphuric acid) can be used, but organic acids are preferable since
they facilitate greater swelling of the collagen.
The oil-in-water emulsions according to the present invention may
also contain soluble biopolymers such as soluble proteins or
soluble polysaccharides. Preferred soluble proteins include gelatin
and pepsin-solubilised collagen. Preferred soluble polysaccharides
include sodium alginate and hyaluronic acid. The soluble biopolymer
may be present in order to regulate the consistency of the
emulsion, for example in the case of gelatin. The soluble
biopolymer may assist in emulsifying and stabilising the emulsion,
for example in the case of gelatin and pepsin-solubilised collagen.
Yet other soluble biopolymers such as alginates and hyaluronic acid
derivatives are known to promote wound healing.
It is envisaged that the oil-in-water emulsions according to the
present invention will preferably be substantially free from added
emulsifiers other than insoluble and soluble biopolymers. However,
in some cases it may be advantageous to include added emulsifiers
such as the well known commercial emulsifiers including lecithins,
mono- and diglycerides of fatty acids and sorbitan esters.
Preferably the oil-in-water emulsions according to the present
invention are medicated. That is to say, the emulsions contain
pharmaceutically active agents intended to assist wound healing.
The emulsions can accommodate both hydrophilic and hydrophobic
active agents.
Hydrophobic pharmaceutically active agents, which tend to partition
into the oil phase of the emulsion, include steroids and retinol.
Hydrophilic pharmaceutically active agents include analgesics,
steroids, antibiotics such as penicillins and cephalosporins,
antiseptics such as chlorhexidine, beta-blockers such as
propanolol, and peptide hormones and growth factors. The
hydrophilic active agents tend to partition into the aqueous phase
of the emulsion. The rate of release of the hydrophilic active
agents is modified by the presence of insoluble protein and
droplets of oil in the emulsion and this allows the rate of release
to be adjusted for different applications by adjusting the protein
and/or the oil content of the emulsion.
The emulsions according to the present invention are particularly
useful as ointments or dressings specifically for the treatment of
burns. The hydrophobic nature of the material (the degree of
hydrophobicity is dependant on the content of the oleaginous phase)
may be used to reduce moisture loss from wounds, to reduce trauma
on removal, or to deliver active agents to the wound site. In these
wound dressings or implants, factors which may promote wound
healing can be incorporated into the matrix, these include growth
factors, glycosaminoglycans (GAGS) such as hyaluronic acid,
chondroitin sulphate or the low molecular weight heparins.
Furthermore additional factors which have potential to reduce wound
scarring such as mannose-6-phosphate, TGF-.beta..sub.3, and anti
TGF .beta..sub.1 and .beta..sub.2 can be dissolved/suspended in
either the hydrophobic or hydrophilic phases of these matrices.
The emulsions according to the present invention may also contain
anti-oxidants to protect the oil, and other preservatives.
The emulsions according to the present invention can be prepared by
homogenising the oil, insoluble protein and water at high shear, to
produce microdroplets of the oil dispersed in an aqueous suspension
of the insoluble protein. Typically, the droplets have a maximum
dimension less than 25 .mu.m, and generally in the range 0.5 .mu.m
to 10 .mu.m.
Homogenisation may be carried out by any suitable means, such as by
a jet homogeniser, ultrasonic homogeniser or blade/shear
homogeniser. The solid or semisolid emulsions may optionally be
heated to 60.degree. C. to 80.degree. C. during or after the
homogenising step. Depending on the temperature of the emulsions
they can be poured, spread or extruded in any desired shape. The
compositions set on cooling.
The emulsions can be extruded or poured onto a secondary wound
dressing, such as a gauze, or onto a backing layer, such as a film.
The resulting layered structure is easier to handle and apply. In
the case of heavily exuding wounds, the emulsions according to the
present invention may not facilitate the removal of exudate from
the wound site. Accordingly, the emulsion films or implants may be
perforated during manufacture so as to assist transmission of
exudate from the wound site to the secondary dressing.
The emulsions according to the present invention are primarily
useful as or in ointments or dressings for the treatment of burns,
wounds or periodontal disease. The emulsions are hydrophobic and
thereby prevent water loss from the burn or wound. Moreover, the
emulsions are non-sticky and do not adhere to the wound tissues
making removal non-traumatic. The emulsions are cool and soothing
on application, especially if previously refrigerated. The
emulsions can provide for controlled release of both hydrophobic
and hydrophilic active agents into the wound.
Solid oil-in-water emulsions according to the present invention
having higher insoluble protein contents may be used as
bioabsorbable wound dressing materials or implants.
The emulsions according to the present invention also have
applications in the cosmetic industry. The fluid emulsions can be
used as creams, while the semisolid emulsions have applications as
emollients and cosmetic bases. Hydrophilic or hydrophobic active
agents specifically adapted for skin care can be incorporated in
the emulsions.
Embodiments of the oil-in-water emulsion according to the present
invention will now be described further, as follows:
EXAMPLE 1
Insoluble Collagen/Oil Emulsion
A. Preparation of Fibrous Collagen from Hide
The insoluble collagen used in the emulsion preparation is
preferably collagen which is pre-washed and rendered largely free
of fat, non-collageneous proteins, polysaccharides and other
carbohydrates as described in U.S. Pat. No. 4,614,794 or U.S. Pat.
No. 4,320,201 or British Patent Spec. No. 1 204 438. The collagen
is suspended in clean deionised pyrogen free water and homogenised
to a fine fibrous suspension by passage through a homogenising
system. Suitable homogenising systems are described in U.S. Pat.
No. 4,320,201. Homogenising may be continued until a desired degree
of fibre division is achieved. This results in a preferred fibre
size of between 0.01 and 10 mm. The collagen can then be used in
this form (as an aqueous slurry) or freeze dried and milled to form
a dehydrated or partially hydrated mass of fibres.
B. Preparation of a Collagen Stabilised Oil-in-water Emulsion
having a Fluid Consistency
The following components were used to prepare the emulsion:
______________________________________ Fibrous Collagen 3.7 g Water
175 ml Vegetable Oil (Sesame Oil) 75 g
______________________________________
The water was chilled to 4.degree. C. and placed in a Waring
Blendor. The collagen (prepared as in A) and oil were then added
and the mixture was homogenised at high speed for a total of 90
seconds. The resulting fluid emulsion showed excellent stability on
standing overnight at 4.degree. C.
EXAMPLE 2
Insoluble Collagen/Oil Emulsion Ointment
An antiseptic ointment consisting of a medicated insoluble collagen
based oil-in-water emulsion was prepared from the following
ingredients:
______________________________________ Insoluble Fibrous Collagen
8.75 g Water 170 ml Vegetable Oil (Sesame Oil) 50 g Chlorhexidine
gluconate 3 g ______________________________________
The water was acidified to pH 4.5 with lactic acid. The acidified
water was chilled to 4.degree. C. and placed in a Waring Blendor.
The collagen (prepared as in Example 1 above), oil and
chlorhexidine gluconate were then added and the mixture was then
homogenised at high speed for a total of 90 secs. The resulting
emulsion has a semi-solid consistency and shows no tendency to
separate into oil and water fractions on prolonged storage at
4.degree. C.
EXAMPLE 3
Solid Oil-in-water Emulsion Stabilised with Insoluble Collagen
The following components were used to form a solid oil-in-water
emulsion stabilised with insoluble fibrous collagen:
______________________________________ Insoluble Fibrous Collagen
18.75 g Water 175 ml Vegetable Oil (arachis oil) 50 g
______________________________________
The water was chilled to 4.degree. C. and placed in a Waring
Blendor. The collagen and oil were then added and the mixture was
homogenised at high speed for a total of 90 secs. The emulsion was
then poured into a tray and cooled to 4.degree. C. whereupon it set
to a solid consistency.
As an alternative, the emulsion can be extruded in any desired
shape at 19.degree. C..+-.4.degree. C. and 345 kPa and then cooled
to 4.degree. C. Preferably the emulsion is extruded as a continuous
sheet.
The solid oil-in-water emulsion may be used as a wound dressing
material.
The above examples are intended for the purpose of illustration
only. Many other embodiments of the present invention as defined in
the accompanying claims will be apparent to the skilled reader.
* * * * *